Ectopic pregnancy (EP), the implantation of a fertilized egg outside the uterine corpus, is a serious acute medical condition that also confers increased risk of substantial future reproductive morbidity, including subsequent ectopic pregnancy and infertility. The U.S. Centers for Disease Control and Prevention (CDC) documented a nearly 4-fold increase in EP occurrence between 1970 and 1989, from 4.5 to 16/1000 reported pregnancies. The most recent U.S. surveillance data, from 1992, estimate lower rates (11/1000 pregnancies), but the shift toward outpatient management of the condition and the reliance on hospitalization records for national surveillance compromise the accuracy of this estimate. Although sparse, available evidence indicates that EP rates may not be declining; and a number of important risk factors-including tubal sterilization, advanced maternal age and Chlamydia trachomatis and other asymptomatic sexually transmitted infections -have become increasingly common. As EP surveillance in the U.S. based on nationally representative sources has become untenable, it has been suggested that other surveillance strategies should be tried, including use of automated databases available at selected healthcare plans. The current application proposes to provide population-based data on long- term (is-year) trends in EP rates within a large U.S. health maintenance organization via analysis of data from an extensive set of administrative data sources. In addition to overall and age-specific trends over time, analyses will include evaluation of inpatient vs. outpatient management and medical vs. surgical treatment modalities. We will also document trends in potentially important etiologic factors during this same interval, including their occurrence among women with ectopic pregnancy. These analyses will provide data to: i) better assess the current status of ectopic pregnancy as a public health problem in the U.S.; 2) evaluate potential risk factors that may merit more in-depth investigation in future etiologic and prevention studies; and 3) provide case selection and programming approaches for establishing more widespread surveillance and evaluation of this condition by aggregating population-based data from healthcare settings with similar resources. [unreadable] [unreadable] [unreadable] [unreadable]